Structurally rigid dopamine d3 receptor selective ligands and process for making them

ABSTRACT

A family of structurally rigid dopamine D3 receptor selective ligands is described. The family of structurally rigid dopamine D3 receptor selective ligands has the formula wherein A is cis or trans —CH═CH—, —C═C—, or cyclohexyl. B is cis or trans —CH═CH— or absent. R1 represents an optionally substituted phenyl group, wherein said substituents are selected from the group consisting of: hydrogen, halogen, amino, nitro, hydroxyl, alkoxy, alkyl, acyl and pyridyl, and said substitution may occur at any of the ortho, meta, or para positions, or R1 represents a heteroaromatic ring. A preferred heteroaromatic ring is indole, quinoxoline, pyridyl, pyrimidyl, or imidazole. R2 and R3 may be independently hydrogen or a halogen, or R2 alone may be C1, C2, or C3 alkoxy, and m is 1 or 2, and n is 0, 1, or 2.

FIELD OF THE INVENTION

The present invention relates generally to a family of structurallyrigid dopamine D3 receptor ligands. The family of structurally rigiddopamine D3 receptor ligands have high affinity and selectivity fordopamine D3 receptors and may be used to treat psychostimulant abuse(e.g., cocaine, amphetamine and derivatives thereof), as well as otherneuropsychiatric and neurodegenerative disorders (e.g., psychosis orParkinson's disease, respectively). In addition, the present inventionrelates to the use of such structurally rigid dopamine D3 receptorligands to image dopamine D3 receptor distribution in vivo, and todiagnose and/or monitor neurodegenerative disorders.

BACKGROUND OF THE INVENTION

The dopamine D3 receptor subtype is a member of the dopamine D2 subclassof receptors. These receptors have been implicated in a number ofcentral nervous system (CNS) disorders including but not limited topsychostimulant abuse, psychosis and Parkinson's disease (Le Foll etal., Eur J Psychiatry 15:140-146 (2000); Joyce, Pharmacol Ther90(2-3):231-259 (2001)). Compounds that bind with high affinity andselectivity to D3 receptors can not only provide important tools withwhich to study the structure and function of this receptor subtype, butmay also have therapeutic implications in these psychiatric andneurologic disorders.

Ger. Offen. DE 4,425,144 (equivalent to U.S. Pat. No. 6,124,294)discloses triazole compounds and their use for treating disorders whichrespond to dopamine D3 ligands. U.S. Pat. No. '294 fails to disclose anycompounds that do not include a triazole ring. Thus all of the compoundsof U.S. Pat. No. '294 are outside the scope of the present invention.Ger. Offen. DE 4,425,143 (equivalent to U.S. Pat. No. 6,342,604)discloses pyrimidine compounds and their use for treating disorderswhich respond to dopamine D3 ligands. U.S. Pat. No. '604 fails todisclose any compounds that do not include a thioether linkage. Thus allof the compounds of U.S. Pat. No. '604 are outside the scope of thepresent invention. Finally, Ger. Offen. DE 4,425,145 (equivalent to U.S.Pat. No. 5,958,923) discloses thiazole compounds and their use fortreating disorders which respond to dopamine D3 ligands. U.S. Pat. No.'923 fails to disclose any compounds that do not include a thiazolering. Thus, all of the compounds of U.S. Pat. No. '923 are considered tofall outside the scope of the present invention.

The compounds of the invention are useful as imaging agents (PET, SPECT)for D3 receptors in the central nervous system and have utility indiagnosis of disease states related to abnormal D3 receptor function orexpression. Structurally rigid analogs provide selective and orallybioavailable drugs that are superior to currently available D3 receptorligands. These compounds have therapeutic use in treating substanceabuse, especially cocaine and amphetamine, psychosis, and Parkinson'sdisease.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the synthetic scheme used to prepare the structurallyrigid dopamine D3 receptor selective ligands of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a family of structurally rigid dopamineD3 receptor ligands. More particularly, the present invention provides afamily of structurally rigid dopamine D3 receptor ligands having theformula

wherein A is cis or trans —CH═CH—, —CH≡CH—, or cyclohexyl. When A iscyclohexyl, the ring can be in chair or boat conformation.

B is cis or trans —CH═CH— or absent.

R₁ represents an optionally substituted phenyl ring, wherein saidsubstituents are selected from the group consisting of: hydrogen,halogen, amino, nitro, hydroxyl, alkoxy, alkyl, acyl and pyridyl, andsaid substitution may occur at any of the ortho, meta, or parapositions, or R₁ represents a heteroaromatic ring. A preferredheteroaromatic ring is indole, quinoxoline, pyridyl, pyrimidyl, orimidazole.

R₂ and R₃ may be independently hydrogen or a halogen, or R₂ alone may beC₁, C₂, or C₃ alkoxy, and m is 1 or 2, and n is 0, 1, or 2.

Even more particularly, the present invention provides a family ofstructurally rigid dopamine D3 receptor ligands having the formula

wherein A is cis or trans —OCH═CH—, —OCH—CH—, or cyclohexyl. When A iscyclohexyl, the ring can be in chair or boat conformation.

B is cis or trans —CH═CH— or absent.

R₁ represents an optionally substituted phenyl group with the exceptionthat R₁ is not triazole or thiadiazole, wherein said substituents areselected from the group consisting of: hydrogen, halogen, amino, nitro,hydroxyl, alkoxy, alkyl, acyl and pyridyl, and said substitution mayoccur at any of the ortho, meta, or para positions, or R₁ represents aheteroaromatic ring. A preferred heteroaromatic ring is indole,quinoxoline, pyridyl, pyrimidyl, or imidazole. Optionally R₁ may alsoexclude pyrimidine.

R₂ and R₃ may be independently hydrogen or a halogen, or R₂ alone may beC₁, C₂, or C₃ alkoxy, and m is 1 or 2, and n is 0, 1, or 2.

Structure-Activity Relationships (SAR) developed by our laboratory andothers demonstrated that the 2,3-dichloro-substituted or2-methoxy-phenylpiperazine was optimal for high affinity binding at D3,wherein every compound with this substituent was more potent than itsunsubstituted homologue. The optimum alkyl chain length, between theamido-aryl function and the phenylpiperazine was four carbons, when thislinking chain was fully saturated. Although 5-carbon linked compoundsexhibit reasonably high affinity for D3, D2 affinity was also very high,compromising the advantage of D3-selectivity. An amide-linked fluorenylring as R₁ was determined to be optimal when substituted at either the2- or 4-positions. However, when a trans olefin was placed in thehydrocarbon linker between the amide group and the2,3-dichlorophenylpiperazine, the fluorenyl ring could be replaced withthe significantly less lipophilic phenyl ring. The addition of an alkenein the linker chain slightly shortens it and changes the shape of themolecule. Thus, longer chains (5-6 carbons) and/or an additional alkeneprovide an improved binding profile over the fully saturated compounds.Furthermore, replacing the phenyl ring with heteroaryl ring systemsfurther reduced lipophilicity, while retaining or improving high D3affinity and selectivity.

In Formula I, R₂ and R₃ are independently selected and are functionalgroups including, but not limited to, hydrogen, alkoxy, and halogen. Theterm “independently selected” is used herein to indicate that the two Rgroups, i.e., R₂ and R₃, can be identical or different (e.g., R₂ and R₃may both be chloride atoms).

The term “alkyl” is used herein to refer to a branched or unbranched,saturated or unsaturated, monovalent hydrocarbon radical having from 1-8carbons, cycloalkyls (3-7 carbons), cycloalkylmethyls (3-8 carbons) andarylalkyls. Suitable alkyl radicals include, for example, methyl, ethyl,n-propyl, i-propyl, 2-propenyl (or allyl), n-butyl, t-butyl, i-butyl (or2-methylpropyl), cyclopropylmethyl, i-amyl, n-amyl, hexyl, etc. As usedherein, the term alkyl encompasses “substituted alkyls.” The term“substituted alkyl” refers to alkyl as just described including one ormore functional groups such as lower alkyl, aryl, aralkyl, acyl, halogen(i.e., alkylhalos, e.g., CF₃), hydroxyl, amino, acylamino, acyloxy,alkoxyl, mercapto and the like. These groups may be attached to anycarbon atom of the lower alkyl moiety.

The term “alkoxy” is used herein to refer to the —OR group, where R is alower alkyl, substituted lower alkyl, aryl, substituted aryl, aralkyl orsubstituted aralkyl. Suitable alkoxy radicals include, for example,methoxy, ethoxy, phenoxy, t-butoxy, etc.

The term “lower alkyl” means C₁ to C₃.

The term “aryl” refers to an aromatic substituent which may be a singlering or multiple rings which are fused together, linked covalently, orlinked to a common group such as an ethylene or methylene moiety. Thearomatic ring(s) may include phenyl, naphthyl, biphenyl, diphenylmethyl,2,2-diphenyl-1-ethyl, and may contain a heteroatom, such as thienyl,pyridyl and quinoxalyl. The aryl group may also be substituted withhalogen atoms, or other groups such as nitro, carboxyl, alkoxy, phenoxy,and the like. Additionally, the aryl group may be attached to othermoieties at any position on the aryl radical which would otherwise beoccupied by a hydrogen atom (such as 2-pyridyl, 3-pyridyl and4-pyridyl). As such, the terms “arylalkyl” and “aryloxyalkyl” refer toan aryl radical attached directly to an alkyl group (e.g.,3(2-pyridyl)propyl)) or an oxygen which is attached to an alkyl group,respectively.

The term “acyl” is used herein to refer to the group —C(O)R, where R ishydrogen, alkyl or substituted alkyl, aryl, or substituted aryl asdefined above.

The term “cyano” is used herein to refer to the group —CN.

The term “halogen” is used herein to refer to fluorine, bromine,chlorine, and iodine atoms.

The term “hydroxyl” is used herein to refer to the group —OH.

The term “nitro” is used herein to refer to the —NO₂ group.

The term “amino” is used herein to refer to the group NRR′, where R andR′ may independently be hydrogen, lower alkyl, substituted lower alkyl,aryl, substituted aryl or acyl.

Within the scope of formula I, certain embodiments are preferred, namelya compound having the formula II:

or the formula III:

or the formula IV, wherein the carbon chain linker is in cisconfiguration:

In formulas II, III, and IV, R₁ and A are the same as defined above.Other preferred compounds are presented in Table 1, below.

Based on their neurochemical and behavioral properties, the structurallyrigid dopamine D3 receptor selective ligands of the present inventionare useful as therapeutics for the treatment of psychostimulant abuse,such as cocaine, amphetamine and derivatives thereof.

It should be noted that dopamine D3 selective agents are preferred overnonselective D2/D3 receptor ligands or dopamine transporter ligands forthe treatment of psychostimulant abuse, as they will not demonstrate acocaine-like behavioral profile or have abuse potential. Furthermore,the structurally rigid dopamine D3 ligands of the present invention willnot have other negative (extrapyramidal) side effects associated withthe dopamine D2 class of therapeutic agents (ex. Haloperidol).Furthermore, dopamine D3 receptor antagonists have been shown, in animalmodels, to extinguish cocaine-seeking behavior and thus will be usefulin reducing craving.

As such, in another aspect, the present invention provides a method oftreating psychostimulant abuse in a subject, the method comprisingadministering to the subject a therapeutically effective amount of acompound disclosed herein.

As used herein, “psychostimulant abuse” has its conventional meaning,i.e., misuse or addiction of a psychostimulant, such as cocaine,amphetamine and derivatives thereof. Typically, cocaine is taken by aperson due to a craving for cocaine generated by its prior use. Cocaineis abused when it is used for gratification, producing effects notrequired or recommended for therapy. The resultant high use of cocaineproduces many serious and adverse side effects. As such, it is highlydesirable to reduce the number and/or intensity of episodes in which aperson experiences a craving for the substance or, more preferably, toeliminate the craving episodes entirely. Dopamine D3 antagonists orpartial agonists have demonstrated utility in reducing craving in animalmodels (Pilla, M. et al. Nature 400:371-375 (1999), Vorel, S. R. et al.J. Neurosci. 22:9595-9603 (2002), DiCiano, P. et al.Neuropsychopharmacology 28:329-338 (2003)).

“Treatment” or “treating,” as used herein, refers to any administrationof a compound of the present invention and includes: (i) inhibiting thesymptoms of the disease, e.g., cocaine addiction; and/or (ii) lesseningor inhibiting the long term effects of the disease, e.g., cocaineaddiction. In therapeutic applications, compositions are administered toa patient already suffering from the disease, e.g., cocaine addiction orParkinson's disease, in an amount sufficient to cure or at leastpartially arrest the symptoms of the disease and its complications. Anamount adequate to accomplish this is defined as a “therapeuticallyeffective amount or dose.” Amounts effective for this use will depend onthe severity and course of the disease, previous therapy, the patient'shealth status and response to the drugs, and the judgment of thetreating physician.

In conjunction with the foregoing method, the present invention providespharmaceutical compositions comprising a compound disclosed herein and apharmaceutically acceptable diluent, carrier or excipient. While it ispossible to administer the active ingredient of this invention alone, itis preferable to present it as part of a pharmaceutical formulation. Theformulations of the present invention comprise at least one compounddescribed herein in a therapeutically or pharmaceutically effective dosetogether with a pharmacologically or therapeutically acceptable carrier.The phrase “pharmaceutically or therapeutically acceptable carrier,” asused herein, refers to a carrier medium which does not interfere withthe effectiveness of the biological activity of the active ingredientsand which is not toxic to the host or patient.

The pharmaceutical compositions of the present invention can be in avariety of forms. These include, for example, solid, semi-solid andliquid dosage forms, such as tablets, pills, powders, liquid solutionsor suspensions, liposomes, injectable and infusible solutions. Inhalablepreparations, such as aerosols, are also included. Preferredformulations are those directed to oral, intranasal and parenteralapplications, but it will be appreciated that the preferred form willdepend on the particular therapeutic application at hand. The methodsfor the formulation and preparation of therapeutic compositionscomprising the compounds of the invention are well known in the art andare described in, for example, REMINGTON'S PHARMACEUTICAL SCIENCES (MackPublishing Company, Philadelphia, Pa., 17th ed. (1985)), THE MERCK INDEX11th Ed., (Merck & Co. 1989), and Langer, Science 249: 1527-1533 (1990),the teachings of which are incorporated herein by reference.

For parenteral administration, for example, the pharmaceuticalcompositions comprise a solution of a compound of the present invention,as described above, dissolved or suspended in an acceptable carrier,preferably an aqueous carrier. A variety of aqueous carriers can be usedincluding, for example, water, buffered water, 0.4% saline, 0.3%glycine, hyaluronic acid and the like. These compositions may besterilized by conventional, well-known sterilization techniques or, theymay be sterile filtered. The resulting aqueous solutions may be packagedfor use as is or lyophilized, the lyophilized preparation being combinedwith a sterile solution prior to administration. The compositions maycontain pharmaceutically acceptable auxiliary substances as required toapproximate physiological conditions including pH adjusting andbuffering agents, wetting agents and the like, such as, for example,sodium acetate, sodium lactate, sodium chloride, potassium chloride,calcium chloride, sorbitan monolaurate, triethanolamine oleate, etc.

For solid compositions, conventional nontoxic solid carriers may be usedwhich include, for example, pharmaceutical grades of mannitol, lactose,starch, magnesium stearate, sodium saccharin, talcum, cellulose,glucose, sucrose, magnesium carbonate, and the like. For oraladministration, a pharmaceutically acceptable nontoxic composition isformed by incorporating any of the normally employed excipients, such asthose carriers previously listed, and generally about 10% to about 95%of the active ingredient and, more preferably, about 25% to about 75% ofthe active ingredient.

For aerosol administration, the compounds of the present invention arepreferably supplied in a finely divided form along with a surfactant andpropellant. The surfactant must, of course, be nontoxic, and preferablysoluble in the propellant. Representative of such agents are the estersor partial esters of fatty acids containing from 6 to 22 carbon atoms,such as caproic, octanoic, lauric, palmitic, stearic, linoleic,linolenic, olesteric and oleic acids with an aliphatic polyhydricalcohol or its cyclic anhydride. Mixed esters, such as mixed or naturalglycerides may be employed. A carrier can also be included as desired,as with, e.g., lecithin, for intranasal delivery.

Once improvement of the patient's conditions has occurred, a maintenancedose is administered if necessary. Subsequently, the dosage or thefrequency of administration, or both, can be reduced, as a function ofthe symptoms, to a level at which the improved condition is retained.When the symptoms have been alleviated to the desired level, treatmentcan cease. Patients can, however, require intermittent treatment on along-term basis upon any recurrence of the disease symptoms.

In general, a suitable effective dose of the compounds of the presentinvention will be in the range of 0.05 to 1000 milligram (mg) perrecipient per day, preferably in the range of 0.1 to 100 mg per day. Thedesired dosage is preferably presented in one, two, three, four or moresubdoses administered at appropriate intervals throughout the day. Thesesubdoses can be administered as unit dosage forms, for example,containing 0.01 to 1000 mg, preferably 0.01 to 100 mg of activeingredient per unit dosage form. Again, the desired dosage will dependon, for example, the particular compound employed, the disease to betreated, the manner of administration, the weight and general state ofhealth of the patient, and the judgment of the prescribing physician.

Moreover, based on their neurochemical and behavioral properties, thestructurally rigid D3 receptor selective ligands of the presentinvention are useful as imaging probes for dopamine D3 receptors and asimaging probes for neurodegenerative disorders (e.g., Parkinson'sdisease) As such, in another aspect, the present invention provides amethod of selectively imaging dopamine binding sites of the centralnervous system of a subject, such as the brain of a human patient, themethod comprising:

(a) administering to the human an inventive compound of the presentinvention; and

(b) detecting the binding of the compound to the central nervous systemtissue, such as the dopamine D3 receptors in the brain.

Moreover, in yet another aspect, the present invention provides a methodfor detecting or monitoring a disease resulting from abnormaldistribution and/or density of dopamine D3 receptor in the centralnervous system of a subject, comprising:

(a) administering to the subject a detectably labeled compound of theinvention;

(b) detecting the binding of that compound to dopamine D3 receptor inthe central nervous system tissue;

(c) determining the distribution and/or density of the dopamine D3receptor in the central nervous system tissue;

(d) comparing the distribution and/or density obtained in (c) with thedistribution and/or density of dopamine D3 receptor in a correspondingnormal tissue; and

(e) diagnosing a disease state by a difference in the distributionand/or density between the normal tissue and the subject tissue.

In a presently preferred embodiment, the structurally rigid dopamineselective ligands of the present invention are labeled with aradioactive label using standard labeling techniques known to and usedby those of skill in the art. Suitable labels include, but are notlimited to: ¹²³I, ¹¹C, ¹⁸F, or ⁹⁹Tc. In addition, binding of thedopamine D3 receptor selective ligands to the brain, such as limbicbrain regions, including the islands of Calleja, is detected usingmethods known in the art, such as positron emission tomography (PET) orsingle-photon emission computed tomography (SPECT). (See, e.g., Yokoi F.et al., Neuropsychopharmacology 27(2):248-59(2002); Pilowsky L. S., NuclMed Commun 22(7):829-33(2001); Soares JC and Innis RB, Biol Psychiatry46(5):600-15(1999); and Videbaek C, J Cereb Blood Flow Metab21(1):92-7(2001), the teachings of which are incorporated herein byreference). Preferably SPECT imaging employs gamma-emitting derivativesof the ligands described herein (e.g., dopamine D3 receptor selectiveligands labeled with ¹²³I or ⁹⁹Tc). Yokoi et al. (supra) have mapped thenormal distribution of dopamine D2 and D3 receptors in humans. Usingthis method, one can diagnose and/or monitor neurodegenerativedisorders, such as Parkinson's disease, characterized by the progressivedegeneration of dopamine nerve terminals.

The invention will be described in greater detail by way of specificexamples. The following examples are offered for illustrative purposes,and are intended neither to limit nor define the invention in anymanner.

EXAMPLES

The compounds of the present invention can be prepared using thesynthetic scheme set forth in FIG. 1. In general, potassium phthalimideis reacted with the dihalo-butene (e.g., trans-1,4-dichloro-2-butene) ordihalo-cyclohexane in aprotic solvent (e.g., dimethylformamide). Theresulting intermediate is then reacted with the appropriatelysubstituted phenyl piperazine (e.g., 2,3-dichlorophenyl-piperazine) togive the N-protected intermediate which is then deprotected withhydrazine to give the desired phenyl-piperazino-amine (e.g.,but-2-enyl). Reaction with the appropriately substituted aryl-carboxylicacid chloride, under biphasic conditions gives the desiredamido-products.

Example 1

The following example illustrates synthesis of a specific compounddisclosed herein. Steps 1-4 illustrate, the synthetic steps to form thedesired phenyl-piperazino-amine. Step 4 illustrates the synthetic stepto form the desired amido end product.

Step 1: 2-(4-Chloro-but-2-enyl)-isoindole-1,3-dione

Trans-1,4-dichloro-2-butene (1.14 ml, 10.8 mmol) was dissolved in DMF(27 ml) and purged with argon. Potassium pthalamide (1.00 g, 5.40 mmol)was added to the solution and the reaction was allowed to stir at roomtemperature overnight. The reaction was then poured into water (75 ml),which precipitated a white solid. This solid was collected by filtrationand purified using silica gel chromatography (3:1 Hex: EtOAc) to afforda 76% yield (961 mg) of a white solid.

Step 2:2-{4-[4-(2,3-Dichloro-phenyl)-piperazin-1-yl]-but-2-enyl}-isoindole-1,3-dione

A suspension of 4-(2,3-dichloro-phenyl)-piperazine (7.55 g, 32.8 mmol),2-(4-trans-chloro-but-2-enyl)-isoindole-1,3-dione (7.73 g, 32.8 mmol)and sodium bicarbonate (13.7 g, 161 mmol) in acetonitrile (100 ml) washeated to 80° C. under an atmosphere of argon for 5 h. After that time,most of the inorganic salts were removed by filtration of the hotreaction mixture. The title compound crystallized out of the filtrateand was taken up in a minimum amount of chloroform. After filtration andevaporation of the solvent, 10.9 g (77%) was obtained as a solid.

Step 3: 4-[4-(2,3-Dichloro-phenyl)-piperazin-1-yl]-but-2-enylamine

To a solution of2-{4-[4-(2,3-Dichloro-phenyl)-piperazin-1-yl]-but-2-enyl}-isoindole-1,3-dione(5.12 g, 11.9 mmol) in absolute ethanol (100 ml) under an atmosphere ofargon was added hydrazine (0.75 ml, 24 mmol), and the reaction mixturewas refluxed for 2.5 h. The ice-cold reaction mixture was filtered andsolvent was removed under reduced pressure. The residue was purified bycolumn chromatography to yield 2.63 g (74%) as yellow oil.

Step 4: Amidation Reaction—Representative Examples Method (a):N-{4-[4-(2,3-Dichloro-phenyl)-piperazin-1-yl]-but-2-enyl}-4-iodo-benzamide(EEC 17)

4-Iodobenzoic acid (456 mg, 3.00 mmol) was refluxed with thionylchloride (3 ml) for three hours. Excess thionyl chloride was removed bydistillation followed by addition and distillation of dry toluene (3×5ml) to give the acid chloride, which was used in the amidation reactionwithout further purification. A solution of the acid chloride (0.21 g,0.83 mmol) in amylene stabilized chloroform (1.4 ml) was added slowly at0° C. to an emulsion of4-[4-(2,3-Dichloro-phenyl)-piperazin-1-yl]-but-2-enylamine (0.25 g, 0.83mmol), amylene stabilized chloroform (8.3 ml), sodium bicarbonate (0.42g, 5.0 mmol) and water (4.2 ml). The reaction mixture was allowed tostir at room temperature for 1 hour and after that time the aqueouslayer was extracted with chloroform (3×5 ml). The organic layer was thenwashed once with water, dried with magnesium sulfate, filtered andevaporated to dryness. The residue was purified by recrystallization ofits oxalic acid salt.

¹H NMR (CDCl₃): δ 2.62 (m, 4H), 3.04-3.06 (m, 6H), 4.06 (m, 2H), 5.75(m, 2H), 6.50 (“It”, “J” 5.4 Hz, 1H), 6.94 (dd, J 6.1, 3.5 Hz, 1H), 7.15(m, 2H), 7.50 (d, J 8.5 Hz, 2H), 7.76 (d, J 8.5 Hz, 2H).

¹³C NMR (CDCl₃): δ 40.43, 50.12, 52.09, 59.07, 97.36, 117.49, 123.46,126.35, 127.46, 128.04, 128.34, 132.66, 132.86, 136.60, 150.06, 165.41.

IR (film): ν 1642, 1584.

Method (b):N-{4-[4-(2,3-Dichloro-phenyl)-piperazin-1-yl]-but-2-enyl}-4-hydroxy-benzamide(PG01015)

1,1′-carbonyldiimidazole (0.18 g, 1.1 mmol) was added to a solution ofthe 4-hydroxy benzoic acid (0.15 g, 1.1 mmol) in absolute pyridine andthe mixture was stirred at room temperature under Argon for 1 h. Afterthat time a solution of4-[4-(2,3-Dichloro-phenyl)-piperazin-1-yl]-but-2-enylamine (0.33 g, 1.1mmol) in 3 ml amylene-stablized chloroform was added and the mixture wasstirred overnight. All volatiles were removed in vacuo and the residuewas purified by chromatography to give 0.23 g (51%) of the titlecompound.

¹H NMR (CDCl₃): δ 2.69 (m, 4H), 3.05-3.08 (m, 6H), 4.01 (m, 2H),5.70-5.75 (m, 2H), 6.67 (t, J 5.5, 1H), 6.76 (d, J 8.6, 2H), 6.88 (m,1H), 7.07-7.19 (m, 2H), 7.56 (d, J 8.6, 2H).

¹³C NMR (CDCl₃): δ 41.23, 50.62, 53.00, 60.01, 115.60, 118.65, 124.75,124.93, 126.66, 127.35, 127.51, 129.00, 131.27, 133.93, 150.74, 160.43,167.71.

IR (film): ν 3309, 1633.

Example 2

The following example shows the calculation of the clogD values.

Calculation of the clogD values has provided guidance towards the designof molecules that are both able to cross the blood brain barrier andhave appropriate biophysical properties for medication development(Table 1). cLOGD values were computed using the software ACD/LOGD suite.These values represent partition coefficients, as measure oflipophilicity, and were calculated at physiological pH of 7.4. Theoptimal range for medication development is 2-5. Molecular modeling hasalso been employed to identify which chemical moieties of previouslyactive molecules are required for D3 selectivity.

Human dopamine D2-long (“D₂”) and D3 (“D₃”) receptors were expressed inHEK cells. In brief, stably transfected HEK cells expressing the humanD2-long and the D3 dopamine receptor were developed using the pIRESbicistronic expression vector (CLONTECH; Palo Alto, Calif.). The levelof expression of D2 or D3 receptors was determined to be greater than2,000 fmoles/mg protein. For comparison, human dopamine D4 (“D₄”)receptors were obtained from HEK 293 cells stably transfected with a PCRproduct of a human cDNA coding for the D4.4 form of the human D4dopamine receptor. The density of binding sites is approximately 1000fmol/mg protein.

Methods for performing in vitro dopamine receptor binding studies aredescribed in Huang et al. J. Med. Chem. 44:1815-1826 (2001) and Luedtkeet al. Synapse 38:438-439 (2000), the contents of which are herebyincorporated by reference. In brief, radioactively labeled dopamineselective ligands bind with picomolar affinity and nonselectivity to D₂and D₃ dopamine receptors expressed in Sf9 and HEK 293 cells. ¹²⁵I-IABNbinds with 7- to 10-fold lower affinity to human D4.4 dopamine receptorsexpressed in HEK 293 cells. Dissociation constants (Kd) calculated fromkinetic experiments were found to be in agreement with equilibrium Kdvalues obtained from saturation binding studies. Saturation plots of thebinding of ¹²⁵I-IABN with rat caudate membrane preparations weremonophasic and exhibited low nonspecific binding. The pharmacologicprofile of the binding of ¹²⁵I-IABN to rat caudate was found to beconsistent with a D₂-like receptor, suggesting that in the caudate theligand binds primarily to D₂ dopamine receptors. IABN was found to bindwith low affinity to sigma σ1 and σ2 binding sites, as well as to D_(1a)dopamine receptors. Quantitative autoradiographic studies using ratbrain indicated that ¹²⁵I-IABN selectively labels the striatum and theolfactory tubercle area, which is consistent with the labeling receptorsexpressed in HEK cells. Therefore, ¹²⁵I-IABN appears to be a highaffinity, selective antagonist at D₂-like dopamine receptors.

Table 1 shows preferred compounds of the invention having the formulaII, wherein R₁ and A are defined as below. The compounds were preparedaccording to the method described in Example 1, and the amidationreaction of step 4 was carried out via method (a) or method (b), asnoted. The clogD values were determined in accordance with Example 2.Table 2 shows binding data in cloned human D3, D2, and D4 receptors inHEK cells. TABLE 1 Synthetic methods and formulas of preferred D3ligands Compd R₁ A Method Formula clogD PG01014

a C₂₁H₂₂Cl₂FN₃O.2HCl 4.64 PG01011

a C₂₁H₂₂Cl₂FN₃O.HCl.0.25H₂O 5.31 PG01012

b C₂₁H₂₂Cl₂FN₃O.1.5HCl.H₂O 5.74 PG01009

a C₂₁H₂₂Cl₃N₃O.HCl.1.25H₂O 5.18 EEC 063

a C₂₁H₂₂Cl₃N₃O.(COOH)₂.CH₃COCH₃ 5.86 PG01007

a C₂₁H₂₂Cl₃N₃O.HCl.0.5H₂O 5.77 PG01018

b C₂₁H₂₂Cl₂IN₃O.HCl.H₂O 5.62 EEC 019

a C₂₁H₂₂Cl₂IN₃O.(COOH)₂ 6.31 EEC 017

a C₂₁H₂₂Cl₂IN₃O.(COOH)₂ 6.21 PG01027

a C₂₂H₂₅Cl₂N₃O₂.(CHCOOH)₂.0.5H₂O 4.82 EEC 069

a C₂₂H₂₅Cl₂N₃O₂.(CHCOOH)₂.0.5H₂O 4.65 EEC 067

a C₂₂H₂₅Cl₂N₃O₂.(COOH)₂.H₂O 5.18 PG01025

b C₂₁H₂₃Cl₂N₃O₂.2HCl 5.31 PGO1015

b C₂₁H₂₃Cl₂N₃O₂.2HCl.0.5H₂O 4.61 PG01029

a C₂₁H₂₂Cl₂N₄O₃.HCl.1.5H₂O 5.29 PGO1013

a C₂₁H₂₂Cl₂N₄O₃.2HCl 4.92 EEC 027

a C₂₁H₂₂Cl₂N₄O₃.2(COOH)₂.1.5H₂O 5.17 PG01038

b C₂₁H₂₄Cl₂N₄O.2HCl.H₂O 4.77 PG01026

b C₂₁H₂₄Cl₂N₄O.3HCl.0.33CHCl₃ 4.04 PG01034

a C₂₀H₂₂Cl₂N₄O.3HCl 3.93 PG01022

a C₂₀H₂₂Cl₂N₄O.3HCl.1.25H₂O 4.15 PG01035

a C₂₀H₂₂Cl₂N₄O.3HCl.0.5H₂O 3.75 PG01020

b C₂₃H₂₃Cl₂N₅O.(COOH)₂.0.25H₂O 4.92 PG01055

b C₂₃H₂₃Cl₂N₃O₂.HCl.H₂O 5.86 PG01030

a C₂₃H₂₃Cl₂N₃OS.(COOH)₂ 7.10 PG01037

b C₂₆H₂₆Cl₂N₄O.2HCl.3H₂O 5.31 PG01041

b C₂₆H₂₆Cl₂N₄O.(COOH)₂.2H₂O 5.34 JJC 2- 069

b C₂₈H₂₇Cl₂N₃O.(COOH)₂.1.5H₂O 7.07 JJC 2- 084

b C₂₈H₂₇Cl₂N₃O.(COOH)₂.0.5H₂O 7.07 JJC 2- 071

b C₂₈H₂₇Cl₂N₃O.(COOH)₂.0.25H₂O 7.07 JJC 2- 085

b C₂₈H₂₇Cl₂N₃O.(COOH)₂.0.5H₂O 7.07 JJC 2- 068

a C₂₁H₂₃Cl₂N₃O.(COOH)₂.0.5H₂O 5.13 JJC 2- 083

a C₂₁H₂₃Cl₂N₃O.HCl 5.13 JJC 2- 077

*-≡-* b C₂₈H₂₅Cl₂N₃O.(COOH)₂.0.25H₂O 7.04 JJC 2- 078

*-≡-* b C₂₈H₂₅Cl₂N₃O.(COOH)₂ 7.04 JJC 2- 062

*-≡-* a C₂₁H₂₁Cl₂N₃O.(COOH)₂ 5.10

TABLE 2 Binding data in cloned human D₂, D₃ and D₄ receptors in HEKcells Compound D₂ D₃ D₄ D₂/D₃ PG01014 10.1 ± 1.9 1.2 ± 0.1 n.d. 8PG01011  8.8 ± 0.7 1.7 ± 0.4 n.d. 5 PG01012  8.1 ± 2.7 1.0 ± 0.2 n.d. 8PG01009 13.1 ± 5.5 1.3 ± 0.2 n.d. 10 EEC 063 15.0 ± 2.8 2.1 ± 1.1 n.d. 7PG01007  25.0 ± 10.8 1.6 ± 1.0 n.d. 16 PG01018 12.7 ± 4.1 3.8 ± 0.6 n.d.3 ECC 019 28.1 ± 3.0 3.9 ± 1.2 n.d. 7 EEC 017 35.4 ± 7.6 4.2 ± 1.5 n.d.8 PG01027  5.3 ± 3.0 0.6 ± 0.1 n.d. 9 EEC 069  56.9 ± 19.1 4.0 ± 1.6n.d. 14 EEC 067  34.7 ± 11.4 1.2 ± 0.2 n.d. 29 PG01025  7.3 ± 3.2 0.8 ±0.2 n.d. 9 PG01015 13.7 ± 4.8 0.4 ± 0.0 356.3 ± 26.5 34 PG01029 10.5 ±4.5 3.4 ± 0.7 n.d. 3 PG01013 21.9 ± 4.0 2.3 ± 0.5 n.d. 10 EEC 027 19.7 ±3.6 0.6 ± 0.2 460.6 ± 187  33 PG01038 25.6 ± 6.8 2.7 ± 0.8 n.d. 9PG01026 29.0 ± 9.4 2.0 ± 0.4 n.d. 14 PG01034 31.2 ± 3.1 2.0 ± 0.6 n.d.16 PG01022 11.2 ± 5.6 2.2 ± 0.6 n.d. 5 PG01035 17.2 ± 4.2 3.7 ± 0.9 n.d.5 PG01020 70.0 ± 7.6 3.7 ± 0.8 1114 ± 555 19 PG01055 100.9 ± 16.9 2.8 ±0.6 1065 ± 382 36 PG01030 148.7 ± 9.7  1.3 ± 0.5 1771 ± 390 114 PG01037 81.9 ± 20.7 0.7 ± 0.1 504.8 ± 62.5 117 PG01041  63.3 ± 16.5 0.7 ± 0.1485.6 ± 157  90 JJC 2-069  62.9 ± 12.7 8.2 ± 2.3 n.d. 8 JJC 2-084  8.1 ±1.6 1.2 ± 0.5 n.d. 7 JJC 2-071 185.6 ± 8   3.4 ± 2.9 n.d. 55 JJC 2-085 61.1 ± 19.2 3.8 ± 1.4 n.d. 16 JJC 2-068 2.9 ± 1  0.6 ± 0.1 n.d. 5 JJC2-083  2.5 ± 0.9 0.4 ± 0.1 n.d. 6 JJC 2-077 592 ± 27 318 ± 32  n.d. 2JJC 2-078 1650 ± 692 41.5 ± 5.4  n.d. 40 JJC 2-062  491 ± 108 127 ± 10 n.d. 4

Example 3

Functional data on preferred compounds of the invention demonstrating D3antagonism.

To measure D2 and D3 stimulation of mitogenesis (agonist assay) or D2and D3 inhibition of quinpirole stimulation of mitogenesis (antagonistassay), CHOp-cells (human receptor) were seeded in a 96-well plate at aconcentration of 5,000 cells/well. The cells were incubated at 37° C. inα-MEM with 10% FBS, 0.05% penicillin-streptomycin, and 200 μg/mL ofG418. After 48 hours, the cells were rinsed twice with serum-free α-MEMand incubated for 24 hours at 37° C. In the functional assay foragonism, the medium was removed and replaced with 90 μl of serum-freeα-MEM and 10 μl of test compound in sterile water; in the antagonistassay, the test compound was diluted in sterile water plus 30 nMquinpirole. After another 24-hour incubation at 37° C., 0.25 μCi of[³H]thymidine was added to each well and the plates were furtherincubated for 2 hours at 37° C. The cells were then trypsinized, and theplates were filtered and counted as usual in the art. Quinpirole was runon every plate as an internal standard. TABLE 3 D₃ Functional Assayusing Stimulation or Inhibition of Quinpirole Stimulation of Mitogenesisin CHO cells (hD₃) Com- Agonist EC₅₀ Antagonist IC₅₀ pound (nM) ± S.E.M.% Max Stim. ± S.E.M. (nM) ± S.E.M. JJC 2071 173 ± 9.6 44.1 ± 0.9 — JJC2-068 >10,000 — 7.72 ± 1.6  JJC 2-083 >10,000 — 6.00 ± 0.59 JJC2-069 >10,000 — 114.60 ± 31.68 

It is to be understood that the above description is intended to beillustrative and not restrictive. Many embodiments will be apparent tothose of skill in the art upon reading the above description. The scopeof the invention should, therefore, be determined not with reference tothe above description, but should instead be determined with referenceto the appended claims, along with the full scope of equivalents towhich such claims are entitled. The disclosures of all articles andreferences, including patent applications and publications, areincorporated herein by reference for all purposes.

1. A compound having the formula

wherein A is cis or trans —CH═CH—, —C≡C—, or cyclohexyl; B is cis ortrans —CH═CH— or absent; R₁ represents an aromatic substituent which maycontain a heteroatom and is a single ring or multiple rings that arelinked covalently, or that are linked to a common group, wherein R₁ isoptionally substituted on one or more rings, wherein said substituentsare selected from the group consisting of: hydrogen, halogen, amino,nitro, hydroxyl, alkoxy, alkyl, acyl and pyridyl, and said substitutionmay occur at any of the ortho, meta, or para positions; R₂ and r₃ may beindependently hydrogen or a halogen, or r₂ alone may be C₁, C₂, or C₃alkoxy; m is 1 or 2; and n is 0, 1, or
 2. 2. A compound having theformula

wherein A is cis or trans —CH═CH—, —C_C—, or cyclohexyl; B is cis ortrans —CH═CH— or absent; R₁ represents an optionally substituted phenylgroup, wherein said substituents are selected from the group consistingof: hydrogen, halogen, amino, nitro, hydroxyl, alkoxy, alkyl, acyl andpyridyl, and said substitution may occur at any of the ortho, meta, orpara positions, or R₁ represents a heteroaryl group, with the exceptionthat R₁ is not triazole or thiadiazole or benzisoxazole orbenzothiazole; R₂ and R₃ may be independently hydrogen or a halogen, orR₂ alone may be C₁, C₂, or C₃ alkoxy; m is 1 or 2; and n is 0, 1, or 2.3. The compound of claim 1, wherein B is absent, R₂ and R₃ are bothhalogen, m is 1 and n is
 1. 4. The compound of claim 1, wherein B isabsent, R₂ is lower alkoxy, R₃ is H, m is 1 and n is
 1. 5. The compoundof claim 1, wherein R₁ is phenyl substituted by a halogen, an aminogroup, a nitro group, a methoxy group, or pyridyl group.
 6. A compoundhaving the formula:

wherein A is cis or trans —CH═CH—, —C≡C—, or cyclohexyl; and R₁represents an optionally substituted phenyl group, wherein saidsubstituents are selected from the group consisting of: hydrogen,halogen, amino, nitro, hydroxyl, alkoxy, alkyl, acyl and pyridyl, andsaid substitution may occur at any of the ortho, meta, or parapositions, or R₁ represents a heteroaromatic ring, with the exceptionthat R₁ is not triazole or thiadiazole.
 7. A method of treating cocaineabuse in a subject, comprising the steps of: administering to thesubject an amount of a compound of claim 1 effective to inhibit bindingof dopamine to a dopamine D3 receptor in the brain of said subject.
 8. Amethod for selectively imaging dopamine D3 receptor in the centralnervous system of a subject, comprising: (a) administering aradioactively labeled compound of claim 1 to the subject; and (b)detecting the binding of that compound to dopamine D3 receptors in thecentral nervous system of the subject.
 9. A method for detecting ormonitoring a disease resulting from abnormal distribution and/or densityof dopamine D3 receptor in the central nervous system of a subject,comprising: (a) administering to the subject a detectably labeledcompound of claim 1; (b) detecting the binding of that compound todopamine D3 receptor in the central nervous system tissue; (c)determining the distribution and/or density of the dopamine D3 receptorin the central nervous system tissue; (d) comparing the distributionand/or density obtained in (c) with the distribution and/or density ofdopamine D3 receptor in a corresponding normal tissue; and (e)diagnosing a disease state by a difference in the distribution and/ordensity between the normal tissue and the subject tissue.
 10. The methodof claim 8 or 9, wherein the central nervous system tissue is braintissue.
 11. A compound having the formula

wherein A is cis or trans —CH═CH—, —C≡C—, or cyclohexyl; B is cis ortrans —CH═CH— or absent; R₁ represents an aromatic substituent which maycontain a heteroatom and is a single ring or multiple rings that arefused rings or are linked covalently, or that are linked to a commongroup, wherein R₁ is optionally substituted on one or more rings,wherein said substituents are selected from the group consisting of:hydrogen, halogen, amino, nitro, hydroxyl, alkoxy, alkyl, acyl andpyridyl, and said substitution may occur at any of the ortho, meta, orpara positions, with the exception that R₁ is not triazole orthiadiazole or benzisoxazole or benzothiazole; R₂ and R₃ may beindependently hydrogen or a halogen, or R₂ alone may be C₁, C₂, or C₃alkoxy; m is 1 or 2; and n is 0, 1, or
 2. 12. The compound of claim 11,in which A is cyclohexyl.
 13. A method of treating cocaine abuse in asubject, comprising the steps of: administering to the subject an amountof a compound having the formula

wherein A is cis or trans —CH═CH—, —C≡C—, or cyclohexyl; B is cis ortrans —CH═CH— or absent; R₁ represents an aromatic substituent which maycontain a heteroatom and is a single ring or multiple rings that arefused rings or are linked covalently, or that are linked to a commongroup, wherein R₁ is optionally substituted on one or more rings,wherein said substituents are selected from the group consisting of:hydrogen, halogen, amino, nitro, hydroxyl, alkoxy, alkyl, acyl andpyridyl, and said substitution may occur at any of the ortho, meta, orpara positions; R₂ and R₃ may be independently hydrogen or a halogen, orR₂ alone may be C₁, C₂, or C₃ alkoxy; m is 1 or 2; and n is 0, 1, or 2;effective to inhibit binding of dopamine to a dopamine D3 receptor inthe brain of said subject.
 14. A method for selectively imaging dopamineD3 receptor in the central nervous system of a subject, comprising: (a)administering a radioactively labeled compound having the formula

wherein A is cis or trans —CH═CH—, —C≡C—, or cyclohexyl; B is cis ortrans —CH═CH— or absent; R₁ represents an aromatic substituent which maycontain a heteroatom and is a single ring or multiple rings that arefused rings or are linked covalently, or that are linked to a commongroup, wherein R₁ is optionally substituted on one or more rings,wherein said substituents are selected from the group consisting of:hydrogen, halogen, amino, nitro, hydroxyl, alkoxy, alkyl, acyl andpyridyl, and said substitution may occur at any of the ortho, meta, orpara positions; R₂ and R₃ may be independently hydrogen or a halogen, orR₂ alone may be C₁, C₂, or C₃ alkoxy; m is 1 or 2; and n is 0, 1, or 2;to the subject; and (b) detecting the binding of that compound todopamine D3 receptors in the central nervous system of the subject. 15.A method for detecting or monitoring a disease resulting from abnormaldistribution and/or density of dopamine D3 receptor in the centralnervous system of a subject, comprising: (a) administering to thesubject a detectably labeled compound having the formula

wherein A is cis or trans —CH═CH—, —C≡C—, or cyclohexyl; B is cis ortrans —CH═CH— or absent; R₁ represents an aromatic substituent which maycontain a heteroatom and is a single ring or multiple rings that arefused rings or are linked covalently, or that are linked to a commongroup, wherein R₁ is optionally substituted on one or more rings,wherein said substituents are selected from the group consisting of:hydrogen, halogen, amino, nitro, hydroxyl, alkoxy, alkyl, acyl andpyridyl, and said substitution may occur at any of the ortho, meta, orpara positions; R₂ and R₃ may be independently hydrogen or a halogen, orR₂ alone may be C₁, C₂, or C₃ alkoxy; m is 1 or 2; and n is 0, 1, or 2;(b) detecting the binding of that compound to dopamine D3 receptor inthe central nervous system tissue; (c) determining the distributionand/or density of the dopamine D3 receptor in the central nervous systemtissue; (d) comparing the distribution and/or density obtained in (c)with the distribution and/or density of dopamine D3 receptor in acorresponding normal tissue; and (e) diagnosing a disease state by adifference in the distribution and/or density between the normal tissueand the subject tissue.
 16. The method of claim 14 or 15, wherein thecentral nervous system tissue is brain tissue.
 17. Use of a compound ofclaim 11 for imaging of D3 dopamine receptor in a subject or in a tissuesample.
 18. Use of a compound of claim 11 for detecting or monitoring adisease resulting from abnormal distribution and/or density of dopamineD3 receptor in the central nervous system.
 19. Use of a compound ofclaim 11 for formulating a medicament for the treatment of cocaineabuse.
 20. A compound having the formula

wherein A is cyclohexyl; B is cis or trans —CH═CH— or absent; R₁represents an aromatic substituent which may contain a heteroatom and isa single ring or multiple rings that are fused rings or are linkedcovalently, or that are linked to a common group, wherein R₁ isoptionally substituted on one or more rings, wherein said substituentsare selected from the group consisting of: hydrogen, halogen, amino,nitro, hydroxyl, alkoxy, alkyl, acyl and pyridyl, and said substitutionmay occur at any of the ortho, meta, or para positions; R₂ and R₃ may beindependently hydrogen or a halogen, or R₂ alone may be C₁, C₂, or C₃alkoxy; m is 1 or 2; and n is 0, 1, or
 2. 21. A compound having theformula

wherein A is cis or trans —CH═CH—, —C≡C—, or cyclohexyl; B is cis ortrans —CH═CH— or absent; R₁ represents an aromatic substituent which maycontain a heteroatom and is a single ring or multiple rings that arelinked covalently, or that are linked to a common group, or is a groupof three fused rings, wherein R₁ is optionally substituted on one ormore rings, wherein said substituents are selected from the groupconsisting of: hydrogen, halogen, amino, nitro, hydroxyl, alkoxy, alkyl,acyl and pyridyl, and said substitution may occur at any of the ortho,meta, or para positions; R₂ and R₃ may be independently hydrogen or ahalogen, or R₂ alone may be C₁, C₂, or C₃ alkoxy; m is 1 or 2; and n is0, 1, or 2.